Friday, 22 September 2017

My vision for 2050

Having looked back at past couple of years in this post, let us look forward now. I take the year 2050 as a benchmark for a vision that I hope might become reality in the ideal case, based on predictions and also personal wishes and recommendations.

How far will “breeding-back” be by 2050?

By 2050, if things go well for all the projects that exist today, all of them will be rather progressed (33 years mean 11 generations at maximum), and there are good chances that a number of individuals already reached my “second milestone”, uniting all achievable aurochs-like characteristics in one individual. However, I think one should not make illusions on the genetic stability of the populations. Depending on the selection policy and breeding technique of the respective projects or herds, the populations will be more or less progressed and many individuals might resemble the aurochs quite well already, but probably in a variation spectrum that also includes a lot of traits of the founding breeds, and especially a recessive genes tend to remain in a gene pool for a quite long period of time (some undesired colour variants, perhaps also variants responsible for tiny horns etc.).
Nevertheless, let us assume that most projects will have quite satisfying and also impressive results by 2050.

From project A vs B vs C to one big metapopulation

It has been my dreams for several years now that one day, at a point when all projects have achieved a good quantity and quality of animals of progressed generations that there will be no more population separation between the projects and breeds when it makes sense from a breeding perspective to unite them by exchanging individuals. Now, in 2017, it would not make sense yet. For example, if a good Taurus bull of a progressed generation would be sold to a Tauros herd made up of pure or first-generation individuals, the offspring would look good because the Taurus bull already unites a lot of desired traits; if a Tauros bull, on the other hand, was put on a more progressed Taurus herd now, it would just increase the number of undesired traits in the herd while all desired traits are already found in the population (just not in one individual at the same time). Tauros (and the other, more recent projects too) have to create well-mixed populations yet that enable them to pick individuals that contain the full potential of the founding breeds. The Lippeaue herd has a time advance in this respect because they started crossbreeding in 1996 and now have all kind of possible breed combinations in their herd.
Exchange between projects would make sense at a point when all projects have reached a level where the gene pool has been mixed well and animals of a certain quality level are prevalent. At an too early state it would not really make sense. Except of course if one project needs f.e. bigger-horned individuals in general, and adds a large horned individual from another project.

What would be the benefit of exchanging individuals and creating a metapopulation? Alleles have a higher risk of disappearing in smaller populations, and by exchanging individuals from on fractioned population to the other you create a large, diverse metapopulation. One large metapopulation would be more than the sum of several separate lines/breeds from a genetic perspective, for the same reason why one big reserve is more than the sum of several small reserves. It means a larger gene pool, more genetic diversity and therefore healthier populations with a higher degree of adaptability.

It also means that also means that the different “breeding-back” results, Taurus cattle, Tauros cattle, Auerrind cattle, Uruz cattle (if the latter project comes underway), and well-selected Heck cattle will amalgamate into one big, indistinguishable type of very aurochs-like cattle. One would maybe need a new term for those, but I simply suggest to stick with “aurochs-like cattle”.

The creation of the large metapopulation of course requires (a more or less coordinated) cooperation between the projects and breeders.

At least one reserve having a complete megafauna

Currently, there are no reserves that have restored a complete Holocene megafaunal community in Europe. I hope that by 2050 we have at least one reserve that is large enough to support populations of deer, wild boar, cattle, horses, wisent and elk that are prayed on by wolves, lynxes and bears. Only when a reserve is inhabited by the complete faunal assemblage we can watch the interaction between the species properly. Otherwise, such as in the lack of predators or with several other species lacking, some species might be outcompeted by others. This might be the case with cattle at Oostvaardersplassen (more on that in an upcoming post).

Feral populations

This brings me to the next point: feral populations. Nowadays, in 2017, there are three main cattle populations that have a solid history of dedomestication: Chillingham cattle, Betizu and Heck cattle at Oostvaardersplassen. As for the first, today it is a breed represented by two herds that have a century-long history of natural breeding and strong selective pressure for resistance against the local climate and certain diseases. The owners of this special breed will certainly strive for maintaining their existence and I would be happy if single individuals would contribute to the “breeding-back” gene pool in some way (which is why I listed it among my list of alternative breeds for “breeding-back”). Regarding Betizu, this breed also has a century-long history of natural breeding and was not husbanded by humans, and even hunted. It would be interesting to maintain a feral population of this landrace somewhere in its habitat, and I would also like to see it contributing to the “breeding-back” gene pool (which is why it is on the list as well).
While the period the OVP Heck population has been existing is considerably smaller than in the former two cases, the initial morphological diversity was high, as much as the selective pressure due to the limited area size. Therefore the population has already experienced some considerable evolutionary process, which is why I hope this population will not disappear. Whatever is going to happen to Oostvaardersplassen, and even if the cattle will be finally outcompeted in the reserve by deer and horses, I hope that at least some of the cattle there will be saved in some way. However, my favoured scenario for this herd would be an expansion of the reserve, a boost of genetic diversity by adding new aurochs-like cattle (perhaps also in the form of pure individuals of primitive breeds), and best would be the introduction of predators (there are reasons to assume this would put some pressure from the cattle in particular).

As for feral cattle in general, I hope that by 2050 at least some of the aurochs-like populations will be in a state that can be considered feral.

This is my vision for aurochs-like cattle by 2050, and I am pretty confident that these goals can be achieved.

Monday, 18 September 2017

The horn of the last aurochs bull

The last remnant population of aurochs was found in a Polish game reserve in possession of the Polish crown from the 16th century until their extinction in 1627. From about 1600 onwards, the last aurochs were found exclusively in the forest of Jaktorow. It was the first extinction of an animal that was precisely documented. In 1564, the number of living aurochs was already as low as 38. In 1599, there were only 24 aurochs left. The 1602  mentions only four individuals: three bulls and one cow. In 1620 it was reported that the last aurochs bull had died and only one cow was left. In 1630, it was noted that this very last cow died three years ago. I illustrated her presumable lone death with a drawing and a little story here in 2015. The reasons why the last aurochs could not survive were poaching and hunting, cattle diseases, limited space and food as much as several severe winters the aurochs could not cope with in their strongly restricted habitat.
It is a myth that the last individual was hunted or poached, it is also a Wikipedia fabrication that her skull was preserved and sent to the Royal Armoury of Stockholm. Unfortunately no skeletal remains are known from these very recent aurochs. But horns and skins of aurochs from Jaktorow were indeed preserved and ornamented and sent to the nobility, and so was one of the horns of the last aurochs bull.

Some weeks ago I came across high-resulted images of this horn from several useful angles on Wikipedia provided with detailed information by the Royal Armoury of Stockholm.

What is very apparent at first is that the horns are comparably thin and slim, fitting a notion by Anton Schneeberger who visited the Jaktorow population in the 16th century. Aurochs horns from earlier centuries are noticeable thicker and also more curved (for example see here, a photo of medieval drink horns at the National Museum of Copenhagen that might be of aurochs, by Markus Bühler). The curvature seems indeed very meagre also compared to most bony core fossils (which, logically, were still less curved than their horn sheaths that covered them in life). See here, for example.
Even more surprising are the size data for the horn given in the description. Apparently it measures only 34,8 cm in length (!) and only 5,7 cm in diameter. I assume that the bull was fully grown when it died, and even if it was a subadult bull, the horn must have been still quite small proportionally for aurochs standards. It is possible that the overall size of the last aurochs was smaller after all, but Schneeberger still described them as way larger than domestic cattle.
The horns of the last aurochs bull might have resembled those of this Maronesa bull, though probably not oriented as lowly.

Why were the horns of the last aurochs so small and meagre compared to those of earlier centuries and millennia? I see two major factors. One would be trophy hunting. Aurochs horns were regarded as prodigious trophies, and hunting for aurochs with particularly large and impressive horns would be directive selective pressure against such horns, eventually resulting in the horns becoming smaller and less impressive. This effect of trophy hunting has also been observed in elks and African elephants, although I have no written source at hand at the moment. The other and probably more important factor would be the limited habitat and therefore limited food supply. This would have led to a stint in horn volume, especially if the mineral supply (calcium in particular), was low. Perhaps the small size of the horns was partially due to phenotypic plasticity and they would have grown larger horns if they had grown up on an area of sufficient food and mineral supply, but I consider it very likely that much of shrinkage in horn size also had a genetic component.

In any case, it of course provokes the question if the “breeding-back” standards should also include this meagre horn shape and size. I do not recommend it for two reasons. At first, the causes of the meagre horns of the last aurochs remnants were likely anthropogenic. Furthermore, most “breeding-back” results have horns smaller and less curved than the overwhelming maturity of all aurochs populations of all ages and regions, and permitting horns as small and weakly curved as that of the last aurochs bulls might make it even more difficult to move the average horn type found in “breeding-back” results towards what was typical of most aurochs.


Cis van Vuure: Retracing the aurochs: history, morphology and ecology of an extinct wild ox. 2005.

Thursday, 14 September 2017

What has changed since 2011

I have been concerning myself with the aurochs and “breeding-back” since March 2011, so more than six years now, and it is interesting to see how much has changed – and exclusively in a positive direction. I am talking about projects, the animals themselves, the information you can find and the availability of that information.

Where “breeding-back” was in 2011 and where it is now

In 2011, there were basically three breeds/projects: Heck cattle (which itself is not a coordinated “breeding-back” project anymore but merely a breed), Taurus cattle (which is also considered more of a breed, but there is systematic and coordinated “breeding-back” at least in the two main locations, Lippeaue and Hortobagy), and the Tauros Project. Heck cattle is a large but very heterogeneous pool of individuals and there is no coordinated selective breeding plan for the breed as a whole, therefore the individuals of that breed vary dramatically in “quality”. There is an improving process, but only very slowly. Regarding Taurus cattle, the Lippeaue population has produced a number of really good individuals by 2011 and earlier already, and still does. In Hortobagy, Hungary, they started with a quantity phase of building up volume and 2011 was the year of shift towards quality breeding. This is, of course, an on-going process. The Tauros Project was in the beginning of the starting phase in 2011.

Now, in 2017, we have Heck cattle, Taurus cattle, the Tauros Project, the Auerrind Project and the Uruz Project. Heck cattle is still experiencing its process of slow improvement, and I think that breeders become increasingly aware of the breeds usual deficiencies (size, proportions, body and horn shape etc.), so more improvement is to be expected. Taurus cattle in the Lippeaue keep on producing good and very good individuals that are often sold to other locations in Germany, often as breeding bulls, improving the Taurus-Heck gene pool as a whole. In Hortobagy, the numbers rose to more than 500 animals, making it the largest “breeding-back” population and I have seen a lot of very interesting individuals and breed combinations on photos already. The Tauros Project is now really underway, with plenty of herds and also in many countries; I like many of the crossbreeds they have to date, and the numbers are above 100.
The Auerrind Project came into existence in Germany. They are in the starting phase right now, with the first crossbred individuals born already, and are planning to realise  interesting combinations not tried before (such as Chianina x Watussi) and such that I have been wishing to be used on a larger scale for a long time (Sayaguesa x Chianina). Thus you can’t imagine how much I am looking forward to see F2 crosses from the Auerrind Project. For the Uruz Project (the name was, if I may mention this, actually my idea that I suggested to Henri Kerkdijk-Otten; just spelled with an “s”), the situation is unclear at the moment. 

Scientific research

Back in 2011, a lot of questions were less clear than they are now concerning aurochs and cattle genetics, f.e. how are which cattle related to each other and the aurochs, was there local introgression or even domestication and to which extent, where did the aurochs originate and cladogenesis within the species et cetera. Now, this field is studied way better, especially thanks to the full recovery of the genome of a British aurochs from 8.000 years ago. This makes it even possible to genetically reconstruct the species via cloning or CRISPR-Cas9 (what consequences would that have for breeding-back? I am going to cover that in an upcoming post).

Information and its availability

Back in 2011, the information situation on breeding-back was very meagre. The articles on the aurochs, Heck cattle and breeding-back on the German and English Wikipedia were not very extensive, and sometimes full of errors and misinformation (especially those on Heck cattle). I expanded them and corrected errors using literature (mainly from Cis van Vuure and Walter Frisch, but also scientific papers), and also added critique sections to the articles on Heck cattle, which was necessary especially on the German one, were Heck cattle was almost praised as a bred-back aurochs, speaking of “quick and incredible results” and so on. Sometimes I was too critical. I also included passages on primitive breeds, made extra articles on them, also supported with photos, as much as a site on the Tauros Project and for Taurus cattle. Later on, also other people started to expand those respective articles and also contributed a lot, especially since I did not have time that much during the last years due to my studies at the University.

For Taurus cattle, not much was to find on the internet. There were only two PDFs from the ABU showing only a very small number of crossbred, first-generation, a google search for photos did not reveal much either. Then in 2013, I first visited the reserve and presented a lot of photos, and you also definitely find more on google now. Also thanks to a growing number of Taurus-influenced breeding-sites.

Besides the articles on Wikipedia, what also was and is an important source of online information is the Aurochs thread on the Carnivora forum. You find a lot of information, photos, breeds, literature, ideas and inspiration there that often influenced my conceptions and ideas regarding this subject. This thread clearly is a rich resource for anyone who wants to get deeper into the subject, and I believe it contributed a lot to giving the concepts of “breeding-back” a more scientific backbone.

Nowadays it is really easy to find a lot of information on the aurochs itself, primitive cattle breeds, “breeding back” and its projects on the web. Thanks to a lot of people making information easily available on various online sources, and also because some projects, such as the Auerrind Project, have a very good public relations work.

The “aurochs web community”

A very interesting phenomenon of the last years, and certainly a consequence of growing projects and information becoming more easily available, is that a kind of “aurochs web community” has developed.
I have been a dinosaur nerd for a long time and basically still am, and as you can imagine there is a huge dinosaur/paleontology web community that is well organised and connected with dozens of qualitative blogs, a very good Wikipedia, youtube channels, huge mailing lists, qualitative artworks called “paleoart” and so on. This is a consequence of the fact that there are several thousands of paleontology lovers on this world, and many of them being of young age and spending a lot of time on the web.

During the last years, I increasingly noticed that an aurochs web community has developed. Not only are there now a lot of people writing on Wikipedia and expanding the articles with scientific sources, showing that they have dug into the subject and know what they are writing, I also have a lot of blog viewers, commenters and a large audience. The Carnivora aurochs thread is very popular as well. It is not only that a lot of people are into the subject now and I feel the number is rising, a lot of people also are quite knowledgeable on this subject. I get a lot of good questions and remarks via email and on my blog, showing that a lot of people are concerning themselves with this subject and also have a passion for it.
There already was an aurochs community prior to 2011 of course. It included all the aurochs lovers at already where there before the aurochs web community developed, and many of them are Heck cattle breeders or just lovers of extinct animals in general. In Germany, I was told that the members of the VFA, the German Heck cattle breeding association, funnily are a cross-section of the whole society and includes members of all kinds of professions (architects, scientists, farmers etc.) that all share a passion for the wild bovine (the conception of what this bovine actually was like is probably not that homogeneous or strict in this case, otherwise Heck cattle would look quite different today). And of course those who initiated the new projects or worked with “breeding-back” cattle in grazing projects or zoos must also have a passion for the original aurochs. It is certainly one of those animals that have a certain charisma, and I covered that charisma in this post.

But what is different in the case of the aurochs web community is that we have a lot of people probably being active a lot on the web, and consequently many of them might be of comparable age as in the paleo web community. After all, I was 17 years old when I got into the aurochs. It is really funny and enjoyable that this kind of community developed, because I would have never guessed that there is enough potential for a subject that concerns mostly with cattle. Of course the aurochs web community is not even nearly as big as the paleocommunity (yet?), because bovines cannot hold up with dinosaurs. Or can they?

In any case, looking back at all the development in “breeding-back” – the projects, the quality of the animals we see, the amount and availability of information, the rising and surprisingly big interest in this topic – pleases me very much. I would actually say now is the best time for an aurochs fan to live in since 1627.

Wednesday, 6 September 2017

How much authenticity is needed?

My readers will know that I focus a lot on morphological and other visible traits on my blog. Therefore I am sometimes asked how much authenticity in regards to optical traits is needed at all – if a good cow has some white spots, or if the population shows a lot of colour variants and horn shapes, who cares as long as the animals do well in nature? But more importantly, do I focus too much on optical traits?
Isn’t it actually more important that the cattle are resistant against diseases, can live in nature without medical care, do not need calving assistance, show natural instincts such as herding et cetera, know how to defend themselves against predators, are suited to the climate of the reserve they are released in and are able also to cope with harsh conditions and low nutritional food and should not genetic diversity always be a priority for the populations?
Tiny white spots on an otherwise very good Taurus cow: dramatic? Photo by Matthias Scharf
Yes, of course these traits are the most important when you want to release the cattle into nature as part of an ecosystem. But the thing is that we can be rather sure that those traits named above are universal for the primitive landraces used in the projects because they not only look aurochs-like but are less-derived overall, and since they have been spared from overbreeding for high productivity it would be new to me if any of the breeds used is prone to a certain disease, sensitive to harsh conditions or would not show natural instincts in the way described for other breeds (f.e. see this work on the social system of Galloways, which is comparable to that of wild bovines, or Poettinger 2011 on Heck cattle compared to wisent). Of the breeds currently used, I know that at least Maronesa is used to deal with wolves in the region the Tauros Project got their individuals from, and I doubt that other primitive landraces would be helpless around wolves, or know less good how to defend themselves against predators than derived breeds. And even derived cattle do have the natural instincts to defend themselves against predators. Apart from that, landraces have no history of being separated from harsh climate conditions or not having to deal with the low nutritional food their surroundings provide, otherwise they would not be landraces.
Furthermore, we have a lot of feral cattle populations all over the world that established themselves in a lot of different habitats without human help, and these often descended from usual farm cattle and not particularly primitive landraces.
For genetic diversity, the right balance has to be found between creating a physically more or less homogeneous and genetically diverse population. It is a kind of balancing act but all of the projects are aware of the importance of genetic diversity.  

So I think there are good reasons to assume that those vital traits named above are always in the package when using primitive, less derived healthy landraces that have to deal with harsh conditions – which is the case in all “breeding-back” projects. This is why you hear that few about it on this blog. Of course this does not mean that any of the projects should stop caring about these traits – stopping to care about traits bears the danger of having these traits reduced in the long run (this phenomenon is called relaxed selection). But I don’t have the impression that any of the projects neglects the hardiness, health and genetic diversity of their populations.

Which brings us to the next point: how much should we actually care about optical traits? How much resemblance is “enough”, and can “imperfections” (f.e. such as tiny white spots on the belly) be considered trivial?

This is of course a very good question. The first priority, in my opinion, concerns the evolutionary fitness of the animals themselves. It should be as good as possible, so let us have a look at how crucial the traits that breeding-back projects care about are for survival. I already explained that visible traits, therefore size, morphology, coat colour et cetera do have a more or less big influence on the evolutionary fitness of the individuals themselves and the population as a whole in the Dedomestication series. But I am going to sum up why the aurochs-like traits we want in “breeding-back” have an evolutionary advantage:

- Size: the bigger the better cattle can defend themselves and their offspring from predators. Also, large bulls have a direct fitness advantage over a bull of the same morphology of smaller size in mating fights.
- Morphology: cattle with long legs, a slender waist, high processus spinosi resulting in a hump and a muscular and not bulky body (short: the morphology shared by all wild bovines) are faster, more swift and agile and therefore have a direct fitness advantageous over bulky, short-legged and sluggish cattle in defending themselves against predators or intraspecific competition
- Horn shape: The horn shape of the aurochs was functional and not arbitrary. It was advantageous in intraspecific competition by making it easiest to pull, push and drag the opponent (see this post). Other bovines that fight in a similar manner have the same horn shape (yak, kouprey), and even the tusks of mammoth have the same curvature if you look at them standing on your head.
- Colour: spotted calves likely are more prone to get discovered by predators when lying hidden in the bushes as they usually do during the first days. Also, some colour alleles are known to be linked with a risk of cancer because of the reduced melanisation (see the Dedomestication articles). There might be more such pleiotropic effects. 
- Appendages: A short dewlap and small furry udder mean less heat loss than large dewlaps and udders, which is advantageous in winter.
- Sexual dimorphism: sexual dimorphism is the result of the mating system in any species. In cattle, it lead to bulls being way bigger than the cows and both sexes being of a different colour. Competition and female choice therefore favour certain sizes and colours.

However, one might argue that traits that give individuals an intraspecific selective advantage will not have an influence on the survival abilities of the population as a whole, and that is correct. For example, the horn shape of the aurochs was surely advantageous in intraspecific respect, but if all the cattle in the population have deviant horn shapes it does not decrease their evolutional fitness as long as the horns are formidable enough to fight off predators. Or take traits that give a selective advantage for female choice: the number of calves born will not be altered if bulls have different selective success.
So O.K., then let us say all the traits that increase individual fitness only in intraspecific regards does not matter that much for the survival chance of the population as a whole. The other traits will become reinforced or redeveloped by natural selection if they truly serve a purpose anyway, so why caring about them? Especially coat colour has the least effect on the fitness of large animals and sometimes the colour of large herbivores are likely to be the result of mutation and genetic drift – for example, would not the Malayan Tapir be equally camouflaged or even better if it was coloured like its extant relatives and not like a panda*? Or the shiny-red African forest buffalo? And just see the interesting colour variants that appear in wild populations of Plains zebra (here) and wildebeest (here and here). So for colour, the room for possibilities is obviously bigger than the narrow space the confirmed European aurochs colours give us. For example, wouldn’t an aurochs with the colour of this impressive Lidia bull at 5:16 (which is probably the colour variant called “Grullo” caused by the Ds allele on black base colour) be quite well-camouflaged in the landscape of Southern Europe?
As for advantageous morphological traits, if we assume they are evolutionary advantageous and therefore inevitably evolve in a feral population, why should it be necessary to breed for them? Furthermore, large size must not necessarily be a fitness advantage in modern Europe. The last aurochs seemingly decreased in body size due to habitat disruption and limited food availability, and the habitat of the “breeding-back” results would be limited reserves, and therefore dispatched small islands in the ecological sense. And as everybody knows, the island effect tends to shrink down the size of large vertebrates as a result of limited space and food availability. Why breeding for large size then? Breeding smaller cattle would be advantageous for them in the long run, and you could even introduce more individuals in the reserve at a certain point (f.e. if there is a reserve where there is food supply for 200 cattle of 600kg, it means that there is place for 120.000kg of cattle, which, in turn, means that there would be food supply for 300 cattle weighing 400kg), and larger populations mean a higher likelihood for survival. Therefore, maybe nobody needs large aurochs in the Europe of the 21st century. Maybe its time for small aurochs.

* I cannot rule out that the exceptional colour of this tapir species has some selective advantage that is not apparent at first glance. It is just an example.

So why not simply tossing a heterogeneous bunch of cattle of usual or even small size that show the vital ecological and behavioural characteristics that all landraces do into the wilderness and see what happens? At least they would show the ecologic capacity to survive the climate and can live on the natural food supply, do not need medical assistance and so on. And if certain aurochs-like morphological traits would be advantageous, they would develop anyway. So why making the extra effort of breeding for them?
Actually, it increases the likelihood of survival for the population if the aurochs-like traits that are advantageous were already widespread or universal in the population. For example, if half of the cattle, or even all of the cattle, are short-legged, massive and sluggish, they would have a much higher risk of being killed by predators and not defending their offspring successfully, while that risk would be way lower in a population of cattle that already are universally large, long-legged, swift and agile. That also goes for small-sized appendages like udders and dewlaps: if you do not care about these traits in the cattle you are releasing, a number of individuals will have more heat loss and therefore less evolutional fitness than cattle that are aurochs-like in these respects.
Thus, many visible traits do probably have a considerable influence on the evolutional fitness of the cattle, which is why we should care about these traits as well in order to increase the likelihood of survival of the population as a whole.  
Regarding the size, the island effect is a tricky argument at first. Indeed I think it would serve no real good trying to counteract the trend if a feral cattle population does become smaller. For example, I would not be surprised if many of the bulls of the isolated population at Oostvaardersplassen are below the 140cm mark already. But for the future, I hope that there will not be dozens of reproductively isolated islands of aurochs-like cattle but one big, qualitative European metapopulation of aurochs-like cattle. In this case the island effect would be much smaller. Furthermore, should we breed wisents for smaller sizes so that we can release them in higher numbers? Or elks? Yes, the last centuries were bad centuries for large animals, and the 21st is probably the worst, but that does not mean that we have to shrink them down. If we want to conserve them, we have to conserve them in all their biological integrity.

The next point are public relations. It is important to communicate the cattle as a proxy for a wild animal that at some point will be wild animals. Otherwise any projects that involve a true dedomestication of these animals (which is the goal of the Tauros Project or Rewilding Europe) will constantly face critique and public outcries (“oh you can’t let those cute calves starve like that, that’s animal cruelty” – no, it’s not, it is nature, thousands of deer starve each winter and nobody on earth cares since it is regarded as natural). So you have to successfully communicate that those animals are part of nature now, and this works best if the animals also have the looks of wild animals.
Why does it work so well to sell Exmoor Ponies and Koniks as wild horses or nearly wild horses? Both breeds have been actively bred for homogeneous looks (yes, it is evidently proven that they look homogeneous because they were bred for it and that the modern versions of those breeds are actually an invention of the 20th century; for details on the breeding history of the Konik go here, for the Exmoor here), and people are smart enough to know that wild animals are usually very homogenous in looks while domestic animals display a huge variety of morphology and coat colour. So if you want to communicate a population of cattle as a part of nature, it would be best if this population is as homogeneous as possible (of course at the same time keeping it genetically diverse) and nearly impossible if the population is heterogeneous in morphology and colour. That’s why New Forest ponies and Dartmoor ponies are not sold as “wild horses” which cannot deny their domestic ancestry due to their heterogeneous appearance (ironically, in the case of European wild horses there were seemingly more than one colour variant, see here). White spots in particular literally scream "domestic". 
The cattle should also show the physique of  wild animal and a minimum of paedomorphic traits that reveal them as domestic animals. When I got into the aurochs in 2011, and knew only about Heck cattle but not primitive landraces, I was enchanted by how some lineages achieved an aurochs-like colour scheme or impressive horns, but there was always something that kept me from regarding them as phenotypically “reconstructed aurochs”. Something just did not match. When I then discovered all those Southern European landraces with their far less derived morphology and head shape, I realized that it was the usually totally domestic morphology and calf-like faces of Heck cattle that distracted me and made them look a) like domestic animals (what they and all other “breeding-back” results are) and b) “just like any cow” with special colour and horns. And I think it is likely that most people are educated and intuitive enough to tell the body shape of a domestic and a wild animal apart, even if you probably will not hear the explanation “well, the cattle lack high processus spinosi in the shoulder region and the skull shows paedomorphic traits, therefore what you call wild cattle here are clearly domestic animals” from Mr. Everyman who visits a reserve or zoo.

Furthermore, it is advantageous if the cattle make an impressive sight, for touristic and other PR reasons. And the aurochs was a very impressive sight. A large bull with aurochs-like proportions, that moves fast and energetic and is swift and agile will leave a much bigger impression on a visitor than a 140cm bull that looks tired and bored and moves sedate. Not to mention the impressive, elegantly curved large horns. A more or less uniform horn shape that points forwards would certainly be more attractive than horns just pointing anywhere. Apart from that, the colour scheme of the aurochs was very aesthetic. The rich and strong colours, the powerful contrasts of the light markings on the dark base colour, the shiny red of the cows and the deep black of the bulls – a colour scheme that is probably way more eye-catching than just dull brown (not to offend the wisent of course, which is also an extremely impressive animal). Especially fascinating would be the strongly marked sexual dichromatism which is virtually a bovid speciality among mammals (while not that rare in sauropsids) and definitely a wild animal trait. I know that when I was a 8-year-old kid the colour difference between the sexes in the aurochs fascinated me and I kept it in my memory for all those years.

What brings me to the next point: Authenticity. Personally, I want authenticity. It has always been my dream being able to see extinct animals living and in flesh, and in the case of the aurochs, it is possible to see something that comes at least very close. And better than that, it is even possible to restore its ecological niche on its former range using those authentic cattle, with benefits for a lot of other species. So why not grabbing this wonderful opportunity? That’s why I want authenticity, I do not want to have “wild cattle” running around in grullo, roan, spotted or any domestic colours with meagre horns pointing anywhere, for the same reasons I do want wisents to be reintroduced in Europe and not wood bison which would do just as well here. We can achieve a large degree of authenticity, and I want authenticity. And a lot of other people want it too. Enough people so that they started “breeding-back” projects which are all on a good way now, and in sum achieved hundreds of aurochs-like cattle. If you personally don’t want that authenticity, it is up to you, but then it seems like you are not interested in “breeding-back”.

All in all I would say that there are good reasons to breed for a maximum of feasible authenticity, and as long there are many other people who have a passion for that (and I suspect the numbers are rising), there are projects doing so. It will be beneficial for people interested in extinct animals like me, nature enthusiasts and the cattle themselves.